The invention relates to a system for supplying lubricating oil to the bearing of a shaft with a central oil feeding passage open at one end and an oil delivery tube extending into the oil pumping passage.
The higher the rotational speed of rotating shafts, the more critical it becomes to supply its bearings with lubricant. On the one hand it is necessary to assure that the stream of oil is not interrupted, and on the other hand the oil has to be "metered," i.e., fed to the bearing, at a very low rate.
The German Pat. No. 7 59 025 teaches immersing the bottom end of a vertically disposed shaft in an oil reservoir. At very high rotational speeds this kind of method has proven unsatisfactory. A gap forms between the rotating shaft end and the oil, so that a reliable and continuously uniform oil feed is no longer obtained.
The German published patent application No. 21 19 857 discloses a system of the type described above, with a likewise vertical shaft. The oil delivery tube reaching into the oil pumping passage is in communication with the oil reservoir. This method has also proven unacceptable in practice. Because of manufacturing tolerances a certain space has to be maintained between the outer wall of the oil delivery tube and the inside wall of the oil pumping passage in the shaft. Due to this space at least a relatively great proportion of the oil emerging from the oil delivery tube runs directly back into the oil reservoir. The portion that reaches the inner wall of the oil pumping passage cannot be repeatably adjusted. This is true especially in view of varying oil temperatures and the consequently varying viscosity of the oil. Precisely at the high oil temperatures which are reached after long operation at high rotational speeds, however, it is necessary to assure a continuous and measured oil supply.